Prostate cancer, which is one of the most common cancers in Korea, is a very fatal disease in adult male. In the case in which prostate cancer is found at an early stage, it may be easy to treat prostate cancer by prostatectomy or local radiotherapy, but in the case in which prostate cancer metastasizes, a treatment success rate is significantly decreased. Therefore, early detection and an effective treatment method of prostate cancer are required.
As an existing anticancer therapy, anticancer chemotherapy and surgical treatment are general treatment methods. Anticancer chemotherapy has a lot of side effects on normal cells and a treatment duration time is long, such that quality of life for patients may be deteriorated. In addition, it is not easy to apply the existing surgical treatment to old patients, and the prognosis is significantly poor. Therefore, recently, targeted therapy capable of specifically diagnosing tumor cells and selectively treating only the tumor cells has been spotlighted, and various researches into target therapy have been conducted. Particularly, in targeted radiotherapy using a radioisotope, side effects are significantly decreased, and a treatment duration time is short as compared to anticancer chemotherapy, such that the targeted radiotherapy may be applied to old patients or terminal cancer patients.
Prostate cancer may be targeted using a gastrin-releasing peptide receptor (GRP-R (BB2, BRS-2)), which is a receptor specifically over-expressed in a cancer cell membrane. Therefore, research into targeted therapy using bombesin derivatives capable of selectively targeting GRP-R has been actively conducted (177Lu-AMBA: Synthesis and Characterization of a Selective 177Lu-Labeled GRP-R Agonist for Systemic Radiotherapy of Prostate Cancer, J. Nucl. Med. 2006; 47:1144-1152). However, in this targeted therapy, it is very important to have high therapeutic effect in addition to having excellent targeting efficiency to more accurately diagnose a disease. Therefore, the present researchers needed to develop better targeted radiotherapy having more excellent targeting efficiency on tumor as compared to the related art and found that in the case of using a target material having excellent target efficiency to prostate cancer as described above, radiotherapy capable of having more excellent targeting efficiency due to high specificity and more effectively treating prostate cancer may be developed, thereby completing the present invention.
Particularly, prostate cancer may be diagnosed and treated by conjugating the bombesin derivatives, which is an agonist of the GPR-P, with a radioisotope. In the target therapy as described above, the larger an amount of target material concentrated on a targeted tumor site, the higher an accurate diagnostic yield, and the higher the expected therapeutic effect. In addition, the smaller the amount of target material concentrated on normal tissue, the smaller the side effects.